I have two java projects. From project1 I have to call a method of project2. Both the projects are developed using the core java concepts and running seperately. As I know that in this case I will have to use any techniques that remotely invokes the methods(Am I correct?), like RMI, WebServices, JMS etc. I have to very frequently call the method of project2 from project1. What could be the best possible way to achieve this.
Thanks
Are your projects deployed to an application server or servlet container?
You can use web services to expose the method from Project 2. This would be standards based and would allow non-Java projects also in the future to access your service if required.
If it works for you, try to implement it in an asynchronous mode for better performance. Web services allow for asynchronous mode of invocation as well. However, for this, your Project 1 would also need expose a callback method.
EDIT:
I had come across that in Java 6, you can deploy web services outside of servlet container as well. Below link can help.
Standalone web services in Java SE 6
However not sure if this can be used in production environments.
RMI is used in Client-Server architecture. There will be a server program that will implement your interface extending Remote and it will have definitions or calls to other methods at server and it will bind an object. Then you will need a client program that will look up for that object and using that object, it will call methods on Server.
So if your projects are running as Client-Server then you can try this thing.
Next thing you are talking about is WebServices. WebServices provide access to some code written at server to its clients over a network via specific protocols. In this your code will be running on a server and you will access it from your client using Web Service.
Now it is up to you what kind of architecture you are following for your projects and which method is more useful and suitable for your scenerio.
Related
I have a standalone java application that initializes and establishes socket connections, both server and client. The standalone java application have operations such as startConnection, stopConnection, getConnectionStatus, etc.
I would like to develop EJB to access or invoke the standalone java application operations, such as getConnectionStatus. The EJB will be deployed to Glassfish.
If the EJB can access the java application and receive results, would you provide an example, references, and/or implementation strategies?
I am not quite sure what you are trying to do.
You can either create some EJB(s) and include the classes that your application uses in your .jar file, or package that application's jar into your EJB's (.ear or .war) file (depending on how you are deploying). This would statically link the code which runs with a "standalone" application with your EJB(s).
Alternatively, you can add some remote invocation methods to your standalone application and turn it into a server that can accept commands. To do that, you can look at Hessian which can allow you to remote services in your application. Here is one example that I found: https://karussell.wordpress.com/2009/04/10/hessian-web-service-protocol-hello-world-example/
I have had lots of trobule trying to get my head around how to solve this scenario:
We have an integration application that uses Camel for integration. This application also has a REST Api that exposes some services providing information about the application, for instance listing the active routes etc.
I have created a user interface for this using AngularJS that connects to these rest services. My main problem is how can I package this application as a self contained jar-file that provides the user interface and all the camel integration.
My working theory: Use a separate Jetty server to serve the Angular JS files and let Camel expose the REST services. The problem with this is CORS since the REST services reside on another port than the jetty server serving the Web UI.
Some requirements for the solution:
Must be a single self contained jar-file.
The camel integration is the main purpose, the Web UI is secondary
and only used for trouble shooting. No need for a high performance
web container since the Web ui is used by only a handful of users.
I have been struggling with this for a couple of days now and it feels like I am over complicating the solution. Help on how to solve this is greatly appreciated.
You could take a look at hawtio
http://hawt.io/
as that is how we do that, hawtio is a web console for java, and has plugins for Camel. Its built using angularjs, and uses REST to communicate with the local or remote Java JVMs. To make the REST calls easier we use Jolokia.
Jolokia requires an agent to be embedded in the JVM, eg where Camel runs. Then that helps with CORS et all. http://jolokia.org/reference/html/security.html#d0e2490
I'm using a set of APIs developed internally by my company to communicate with some common central services in the organization. The APIs can be configured dynamically by runtime configuration to use several transport protocols as needed by the system.
The collection of internal APIs are coupled to the IBM WebService thinclient.jar to configure and call all the necessary web services. I got the standalone prototype working smoothly, but need to integrate the functionality into several other services that are being developed in Grails.
This is where things fell apart. In the code that I've written, we just call a factory method and use that to get a client session and then proceed with our business logic. Simple. Using the debugger and digging into the API getClient() call, I can see that this gets a generic transport configuration and then binds it to a SOAP transport configuration. From here, the path differs whether it is the pure standalone Java service or the service running in the Grails app.
In the pure Java standalone, this then is bound to a
com.ibm.ws.webservice.engine.client.Service where the
initService() method is called and things work as expected.
In the Grails app, with the same Java code included, the same place
in the code calls to
com.springsource.loaded.ri.ReflectiveIntercepter and then after a
lot of back and forth in the spring-loaded API, it finally throws a
java.lang.reflect.InvocationTargetException.
Does any one have any tips or ideas on how to get the reflection in Grails to behave the same as in the straight Java?
I've tried a lot of variations to get to this point and I'm nearing the end of my rope. Ideally, it would be easiest to manage the Grails service that manages our business logic and the Java code that talks to these internal systems together, so I would prefer to get everything (Grails and my Java service code) working together. I briefly tried building a standalone JAR of my service code and all it's dependencies, but had chained dependency conflicts when trying to use that in Grails. My final option will be to stand my Java service up separately from the business logic in the Grails service and just make the calls from the Grails service to the Java service. This is less than ideal.
It's easy when you stumble into the answer... ;-)
The Grails service runs as expected if I set the run configuration in IDEA to use -noreloading option.
grails -noreloading run-app
This stops Grails/IDEA from leaving in the hooks to reload classes on the fly.
Are there any thoughts on whether this is a bug in Grails or the SpringSource Loader classes?
We have a java server application which runs certain batch jobs. It's core function is not as a web application and there's no reason for it to be that. But we would like to add an option to check what the app is doing from a web page. And we thought this could be nicely done with the Google Web Toolkit.
In any previous experiences we have with GWT we have deployed it on Tomcat. But in this case it seems like overkill. The web part is more of a side function to what the application is actually doing.
I'm thinking of a solution where the web server is integrated into the jar file - perhaps Jetty? So that the full java application can be deployed to a single jar file together with the web/GWT part.
There may be performance aspects to this but the web side of things will have very few users. Are there any other reasons not to do it this way?
And, can you give some advice on how to configure Eclipse / Ant / Jetty / GWT for this?
we had the similar experience at our previous project. There was an eclipse-rcp application, with embedded Jetty server (it was started programmatically when application was starting). GWT application was deployed into the Jetty as usually. Also there was a OSGI-service as a controller to provide communication between GWT-server and other parts of application. GWT server was usual RCP server, which is described in the most of examples. It had a reference to the controller. Moreover, it was an event listener, to support bot-side communication.
The main problem for us I think, was synchronization problem. Since there were a lot of messages between eclipse-rcp application an GWT-part (every let say 100 ms the message was received) and GWT had an asynchronous way of communication between client part and its server part, then some mechanism had to be created to synchronize those messages. Otherwise there were no performance problems (except IE 6. which had to be supported:S :D).
Hope this will somehow help.
Upd: As far as I remember, the controller was registered as OSGI service only to be able to communicate with other services of Eclipse-RCP part. In order to communicate with GWT controller was implementing special interface, which was known to the GWT-server (Controller was registered as an implementer through instantiation and the server was regsitered in the controller as IMessageListener). This interface was lying in separate project, which could was also built into the .war file. This project also contained number of event to support backward communication from controller to GWT-server through IMessageListener interface.
It's kind of confusing probably, sorry. May be I should draw a diagram..
As the title suggests, this is in relation to Java EE and Glassfish in particular.
From what i've learned the application client is executed in some application client that has the ability to talk to glassfish. But there seems to be limitations to this regarding annotations.
Can someone give me an example of the difference in connecting to a glassfish application server from the two different application types?
What is the benefit of the application client approach, and what approach is the most commonly used when developing application clients for Java EE?
The code (work you need to do) associated with connecting to the app server in either case is not really all that hard... but it is covered in different docs.
These are the instructions on how to access an EJB from a stand-alone java application.
These are the instructions for using an app client to access an EJB from a Java EE 6 Application Client with GlassFish v3: http://docs.sun.com/app/docs/doc/820-7695/beakt?l=en&a=view
Accessing an EJB from an application client gives you access to more of Java EE services 'automagically' than if you were working with the EJB 'directly'. You can cobble together access to some of these services in the stand-alone case, but the burden shifts onto the application developer/deployer to make that access work.
Creating a stand-alone application that accesses an EJB will seem easy, in the short term, and many folks will invest in that strategy. If they deploy their client application onto a large number of machines, the burden associated with a cobbled together service access strategy can become a burden.
Deploying an application client that uses the application client container is not free either. The advantage is the fact that you have the support of your app server vendor to overcome deployment issues.
If you are using GlassFish (v2.1,v2.1.1 or v3), you can also take advantage of Java Web Start support, which simplifies client application deployment a lot.
An application client is actually run in a container and has full access to Java EE resources defined on your server in the same way that a Servlet or EJB does. This would typically be used for some type of admin client, not a user application. Here is one explanation.
In addition to the Java EE Application Client, there is also the concept of a Thin Client, which allows access to some Java EE resources as well, but not as easily as the App Client. It usually involves using JNDI lookup with absolute names as JNDI references are not available. A typical case for this would be a standalone producer/consumer of JMS messages. It is basically a lighter weight option of the full App Client.
If you are simply creating a user application, you will most likely want to either use a Thin Client model, or a plain old application that simply consumes services from your Java EE app via servlet or web service calls.